In continuation of an ongoing investigation of human auditory motion perception, a series of new experiments is proposed, in which stimuli will be presented from stationary and moving loudspeakers in an anechoic environment. Standard psychophysical procedures will be employed in all experiments, requiring subjects to make simple button-press or adjustment responses to indicate judgements about the various stimuli presented. The experiments are designed to address three basic questions related to auditory motion perception. The experiments are designed to address three basic question related to related auditory motion perception: (1) What is the role of "binaural sluggishness" in horizontal-plane motion perception of low- and high-frequency stimuli? In particular, does the sluggish binaural responses that is well-documented in earphone experiments underlie the failure to demonstrate a strong perceptual salience of velocity of horizontally moving sounds in the free field? (2) How does the presence of a single reflection (echo) affect human perception of motion, and, conversely, to what extent is the precedence effect (suppression of information about the echo) affected by the horizontal motion of a direct sound? and (3) What are the limits and characteristics of auditory motion perception outside of the horizontal plane (e.g., in oblique planes comprised of both horizontal-and vertical-plane component trajectories)? Results from these experiments will contribute to our understanding of how auditory spatial processing operates under dynamic conditions, both in anechoic and echoic spaces. The basic knowledge gained from these experiments might well have important practical applications for human performance in our dynamic environment.